Cal tubular, scarcely accrescent, with scarious or hyaline intervals between the 5 green and more herbaceous ribs, ruptured by the developing capsule; corolla salverform, with slender tube and abruptly spreading lobes; filaments short, unequally placed in the cor-tube, the anthers included or some of them partly exserted; capsule 3-valved, with 1(-4) seeds per locule, the seeds unchanged when moistened; perennial (seldom annual) herbs or suffrutescent plants with entire, chiefly opposite lvs and handsome fls in terminal or terminal and axillary cymes that may be reduced to a single fl. 50-60, N. Amer. and n. Asia. Allied spp. often hybridize.